My question is what's is the difference between Gigabit Ethernet Controller and Ethernet Converged Network Adapter?

I want to upgrade my server to 10 Gigabit ethernet, my server vendor recommend me one card but it's very expensive and there are other cheaper ethernet card and since they are all connected with PCI to the board I wanted to know can I use any other PCI ethernet card?

The vendor recommended me to purchase Intel 82599 10GbE Daughter Card, Gen 2 PCIe x8 and I was thinking to buy the Intel® Ethernet Converged Network Adapter X540-T2, I didnt wanted to put useless information but if you need any additional information to answer this question I will happy to share it with you.

4 Answers
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Regular Ethernet adapters can ONLY handle regular Ethernet traffic, some offer hardware acceleration while others don't but that's irrelevant. CNAs allow for both regular Ethernet and Data Center Ethernet (DCE) to be transmitted, DCE is a newer protocol that is almost exclusively used for handling Fibre-Channel-over-Ethernet traffic, in fact FCoE demands the use of DCE. Again whether or not a CNA is hardware accelerated is irrelevant to this question, but generally CNAs do offer some degree of acceleration.

Gigabit adapters are designed to be used for Ethernet only. By this I mean that the chip sets that are on them do not have the ability to offload storage protocols (i.e. iSCSI, FCoE). Converged Ethernet adapters do have offload chips that should help speed up certain traffic by moving to them to specialized chips on the Ethernet adapter.

CNAs will show up as an iSCSI hardware adapter or FC adapter if it's enabled and those functions are offloaded to the hardware on the CNA. Data Center Ethernet isn't actually a protocol. Are you thinking about CEE (FCoCEE)?
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MikeyBJan 13 '14 at 22:05

CNAs do MUCH more than simply offload the protocols. They present to the OS as an HBA and abstract the fact that it's actually CEE on the wire.
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MikeyBJan 14 '14 at 19:06

Regular Ethernet adapters can ONLY handle regular Ethernet traffic, some offer hardware acceleration while others don't but that's irrelevant. Any iSCSI (for example) traffic that transits the card is handled by the host, not the NIC.

CNAs allow for both regular Ethernet and Converged Enhanced Ethernet (CEE) to be used. CEE is a newer protocol that is almost exclusively used for handling Fibre-Channel-over-Ethernet traffic, in fact FCoE demands the use of CEE.

Whether or not a CNA is hardware accelerated is irrelevant to this question, but generally CNAs do offer some degree of acceleration.

(some content stolen from Chopper3 and into my own answer since he didn't like my edit :D)

A Converged Network Adapter allows for regular Ethernet traffic but will also handle additional Converged Traffic, such as iSCSI, FCoE and FCIP.

Why should you care? Well, Servers need to connect users and other applications to the application hosted within. The Server also needs to access stored data. These operations are typically separated by physical cards and connectivity i.e. LAN via a standard NIC, and SAN via an HBA. They'd each connect to there own network.

So can you reduce the amount of cabling, adapters, switches, optics etc in your network? This is why a Converged Network Adaptor was introduced.